Modern weapon system development has improved the range, accuracy, rapidity of fire, and lethality of guns and ammunition under a variety of battlefield conditions. The general improvement in weapon lethality supplied to ground troops has made it extremely important for personnel in armored vehicles to spot the enemy and fire an air burst before being fired upon. The amount of time that an armored vehicle commander has to make a decision and see that a fire command is executed can be very short. To overcome or shorten these lift threatening time constraints, personnel in armored vehicles, such as tanks, frequently travel with a round chambered in its gun. The problem with these chambered prior art rounds was that the range is preset and cannot be quickly changed without unchambering the round. Thus an armored vehicle traveling with a chambered round may be at a severe disadvantage, when an air burst is desired, if the preset fuze range is incorrect.